AD/B737/361 Rudder Feel and Centering Unit (Cth)

AIRWORTHINESS DIRECTIVE

For the reasons set out in the background section, the CASA delegate whose signature appears below issues the following Airworthiness Directive (AD) under subregulation 39.001(1) of CASR 1998.  The AD requires that the action set out in the requirement section (being action that the delegate considers necessary to correct the unsafe condition) be taken in relation to the aircraft or aeronautical product mentioned in the applicability section: (a) in the circumstances mentioned in the requirement section; and (b) in accordance with the instructions set out in the requirement section; and (c) at the time mentioned in the compliance section.

Boeing 737 Series Aeroplanes

AD/B737/361 Rudder Feel and Centering Unit 12/2009

Applicability:

Boeing Model 737-600, -700, -700C, - 800, -900 and -900ER series aeroplanes.

Requirement:

1.    For Model 737-600, -700, -700C, -800, and -900 series aeroplanes identified in Boeing Alert Service Bulletin 737-27A1287, dated 16 April 2008:

Perform a test of the rudder pedal forces or a detailed inspection of the inner spring of the rudder feel and centering unit, by doing all the applicable actions, including all applicable corrective actions before further flight, in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin
737-27A1287.

2.    For Model 737-600, -700, -700C, -800, and -900 series aeroplanes identified in Boeing Alert Service Bulletin 737-27A1287:

Replace the spring assembly in the rudder feel and centering unit in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin
737-27A1287.  Accomplishing the replacement ends the repetitive tests or inspections required by Requirement 1 of this AD.

3.    For all aeroplanes:

Do not install, on any aeroplane, a rudder feel and centering unit having part number (P/N) 65C25410-7, serial numbers 3609 through 3820 inclusive, unless it has been modified according to Requirement 2 of this AD.

Note:  FAA AD 2009-19-02 Amdt 39-16019 dated 31 August 2009 refers.

Compliance:

For Requirement 1 - Within 30 days after the effective date of this AD, unless previously accomplished.

Thereafter Repeat the test or inspection thereafter at intervals not to exceed 120 days.

For Requirement 2 - Within 36 months after the effective date of this AD.

For Requirement 3 - As of the effective date of this AD.

This Airworthiness Directive becomes effective on 19 November 2009.

Background: This AD results from reports of low rudder pedal forces that were caused by a broken inner spring in the rudder feel and centering unit; a broken inner spring in conjunction with a broken outer spring would significantly reduce rudder pedal forces.  We are issuing this AD to prevent reduced rudder pedal forces, which could result in increased potential for pilot-induced oscillations and reduce the ability of the flight crew to maintain the safe flight and landing of the aeroplane.

David Villiers
Delegate of the Civil Aviation Safety Authority

28 September 2009